During a packaging process at the wafer level (wafer level packaging=WLP), it is necessary [lacuna] when package sizes correspond to the circuit units, that is to say when packages are designed for the size of the chips (chip size packages=CSP) and are manufactured only in the same size as the circuit units (that is to say the chip size). The circuit units or components to be fitted must in this case be soldered or bonded by one face at the bottom onto generally small solder or gold contacts on a printed circuit board or a module board, with no package being provided (“naked chip”).
Once the circuit units have been mounted, all the connections of the circuit units are thus located on a lower surface of the chip face, that is to say in the “shadow” of the circuit unit (of the chip).
A major disadvantage of conventional methods for fitting circuit units is that, when there are a large number of connections, the distance between these connections (separation distance, pitch) must be reduced in order to accommodate all the connection units under a circuit unit or underneath a silicon surface of the circuit unit. This disadvantageously requires highly costly circuit boards.
A further disadvantage of the methods according to the prior art is that these circuit boards frequently do not comply with any Standard.
Conventional packages or casings for circuit units are therefore constructed using a so-called “fan-out design”, which means that the connection contacts are not fitted directly underneath the lower face of the silicon surface of a chip (of the circuit unit), but that a so-called intermediate contact-making unit (interposer) is provided, whose base area is larger than the actual circuit unit to be fitted, so that it is possible to achieve a standard separation distance (a standard distance between the contact elements).
When using standard packages according to the prior art, one disadvantage is that the intermediate contact-making device (interposer) must be used since these are expensive and disadvantageously also result in a complex assembly process procedure.